בתרומה דרבנן בחמץ דאורייתא מי אמרינן אטו בדיקת חמץ דאורייתא דרבנן היא דמדאורייתא בביטול בעלמא סגי ליה
only with regard to teruma that in modern times is sacred by rabbinic law, as the Torah obligation to separate teruma was abrogated after the destruction of the First Temple. However, with regard to leavened bread, which is prohibited by Torah law, do we say that this principle applies? The Gemara responds: Is that to say that the search for leavened bread is required by Torah law? It is a rabbinic ordinance, as by Torah law, mere nullification is sufficient. Since the issue at hand is not the Torah prohibition of leaven but the rabbinic ordinance to search one’s house, this halakha is comparable to the case of baskets of teruma and non-sacred produce.
צבור אחד של חמץ ולפניו שני בתים בדוקין ואתא עכבר ושקל ולא ידעינן אי להאי על אי להאי על היינו שני שבילין דתנן שני שבילין אחד טמא ואחד טהור והלך באחד מהן ועשה טהרות ובא חבירו והלך בשני ועשה טהרות
The Gemara presents another situation: In a case where there is one pile of leavened bread and before it there are two houses that were searched, and a mouse came and took a morsel from the pile, and we do not know if it entered this house or if it entered that house, this is akin to the case of two paths, as we learned in a mishna: There were two paths, one of which was ritually impure due to a corpse buried there, and one of which was ritually pure. And someone walked on one of them, but he does not remember which, and afterward he engaged in handling items of ritual purity, e. g., teruma or consecrated items; and another person came and walked on the second path, and he too does not remember which path it was, and he also engaged in handling items of ritual purity.
Rabbi Yehuda says: If this one asked a Sage by himself, and that one asked a Sage by himself, they are both pure. When considered separately, each person retains his presumptive status of ritual purity. However, if they both came to ask at the same time, they are both ritually impure. Since one of the two certainly passed on the impure path, even though it is uncertain which, both are deemed impure due to that uncertainty. Rabbi Yosei says: One way or another they are both ritually impure.
Rava said, and some say it was Rabbi Yoḥanan who said: If they came at the same time, everyone agrees that they are ritually impure, as even Rabbi Yehuda concedes that this is the halakha. If they came independently, one after the other, everyone agrees that they are ritually pure. They disagree only with regard to a case where one comes to ask about himself and about the other. Rabbi Yosei likens this case to one where they come to ask at the same time, and Rabbi Yehuda likens it to a case where they come one after the other.
The Gemara addresses another case: If one saw a mouse take leaven and there is uncertainty whether the mouse entered a house that was already searched and uncertainty whether the mouse did not enter that house, that is akin to the halakha of ritual impurity in a valley, and is subject to the dispute between Rabbi Eliezer and the Rabbis.
As we learned in a mishna with regard to one who enters a valley during the rainy season, when seeds are sprouting, people do not have permission to wander in the field of another, as they might harm the plants. For the purpose of this halakha a valley in the rainy season is considered a private domain, and there is a general principle that in the case of uncertainty concerning whether or not one contracted ritual impurity in a private domain he is ritually impure. And if there was ritual impurity in a certain field, and one person said: I walked in that place, in the valley, and I do not know whether I entered that field or whether I did not enter, Rabbi Eliezer deems him pure, and the Rabbis deem him impure.
שהיה רבי אליעזר אומר ספק ביאה טהור ספק מגע טומאה טמא
Rabbi Eliezer deems him pure, as Rabbi Eliezer would say: Concerning uncertainty with regard to entry, i. e., whether or not he entered the place, he is ritually pure; however, if one certainly entered the place and the uncertainty is with regard to contact with ritual impurity, he is ritually impure. According to this opinion, the principle with regard to uncertain impurity in the private domain applies only in a case where the uncertainty is with regard to contact. The Rabbis, however, do not distinguish between these situations, as they maintain he is impure regardless of whether the uncertainty is with regard to entry or with regard to contact. This dispute applies to the case of whether or not one is required to conduct an additional search for leaven in a case where there is uncertainty whether or not leaven was taken into the house.
The Gemara discusses another case: If one saw a mouse enter a house with leaven in its mouth and someone searched and did not find any leaven there, this is akin to the dispute between Rabbi Meir and the Rabbis. As we learned in a mishna, Rabbi Meir would say: Any object that has the presumptive status of ritual impurity, i. e., it is certain that an impure object was buried in a particular place, that place forever remains in its ritual impurity, even if it was excavated and the source of impurity was not found, until it becomes known to you where the ritual impurity is. The assumption is that the impurity was not found because the search was not conducted properly.
וחכמים אומרים בודק עד שמגיע לסלע או לקרקע בתולה
And the Rabbis say in this case: He continues searching until he reaches bedrock or virgin soil, under which there is certainly no ritual impurity. If he searched that extensively and failed to discover any impurity, it is apparently no longer there. This dispute applies to the aforementioned case involving leaven.
The Gemara analyzes yet another case: If one saw a mouse enter a house with leaven in its mouth and one searched and found a crumb of leaven there, but there is uncertainty whether or not the crumb that he found is the crumb that the mouse took into the house, this would be akin to the dispute between Rabbi Yehuda HaNasi and Rabban Shimon ben Gamliel.
As it was taught in a baraita:
With regard to a field in which a grave was lost, i. e., there is certainly a grave located in the field but its precise location is unknown, one who enters the field is ritually impure, as he might have stepped on the grave. If a grave was later found and marked in the field, one who enters and walks on the other parts of the field is ritually pure, as I say: The grave that was previously lost is the grave that was subsequently found. This is the statement of Rabbi Yehuda HaNasi. Rabban Shimon ben Gamliel says: The entire field must be searched, as perhaps the grave discovered is not the one that was lost. This dispute applies to the above case of leaven.
The Gemara discusses another situation: If a person placed nine crumbs of leaven and found ten, indicating that mice had added at least one crumb, this is akin to the dispute between Rabbi Yehuda HaNasi and the Rabbis. As it was taught in a baraita with regard to a person who placed a maneh, one hundred dinars, of second tithe, and found two hundred dinars: Since it is evident that someone came and placed at least one extra maneh there whose status is unclear, the pile is presumed to contain non-sacred money and second-tithe money intermingled with each other. The assumption is that the additional money is non-sacred, and it is impossible to determine which is the non-sacred money and which is the second-tithe money. This is the statement of Rabbi Yehuda HaNasi.
וחכמים אומרים הכל חולין
And the Rabbis say: It is all non-sacred money. Since someone else was clearly involved, it is possible that he took the maneh and left behind two hundred other dinars. Consequently, it is impossible to identify any of this money as the original maneh. This same reasoning can be applied to the case of leaven. Since there were undoubtedly mice present, it is possible that the mice took the crumbs, moved them, and replaced them with other crumbs. As a result, the entire house must be searched again.
הניח עשר ומצא תשע היינו סיפא דתניא הניח מאתים ומצא מנה מנה מונח ומנה מוטל דברי רבי
The Gemara raises the reverse situation. If one placed ten crumbs and found nine, this is comparable to the case mentioned in the latter clause of that same baraita, as it was taught in the baraita: If one left two hundred dinars of second-tithe money and found a maneh, presumably, one maneh from the initial two hundred remains placed, and the other maneh is taken and missing. This is the statement of Rabbi Yehuda HaNasi.
וחכמים אומרים הכל חולין
And the Rabbis say, in keeping with their aforementioned opinion: It is all non-sacred money, as the assumption is that whoever took part of the money actually took it all, and this is a different maneh. Since it is different money, it is presumably non-sacred money, not second-tithe money. This dispute applies to the case where one finds fewer crumbs of leaven than he left.